Choosing the right tire can enhance towing performance and save fuel!

As I write this column, the trailer is hooked up in the driveway and the family is waiting for me to finish this and head on down the road to Prince Edward Island – before we leave home base on one of the Thomson Family Adventures, I always check all of the trailer and tow vehicle tires for proper inflation and signs of wear. This morning, as I was inspecting my tires, I thought back to an e-mail that I received from John in Alberta about a month ago, asking about his Chrysler Pacifica.
            Reflecting on the subject of tires for tow vehicles, I thought that the email exchange we had might be helpful to RV Lifestyle Magazine readers with similar vehicles.
            John and his family live near Lethbridge Alberta and travel to B.C. Headwinds on this stretch of road are legendary so he needs a package that is reasonably aerodynamic and has good performance in third gear. If you like the visual appeal of the Pacifica the new ones have the same 4.0 Litre engine and 6-speed transmission as we have in our Town and Country Van that I have written about previously.

John from Alberta wrote:

Hello Andy:
            I have been a subscriber to your magazine since the New Year and enjoy it tremendously. I own a 2005 Chrysler Pacifica AWD with the touring package. The tires that I am running are 255/55/19". The wheel rims are 9” wide. The trailer that I have in mind is the R-vision Trail Cruiser 23 footer with the rear slide out. My questions is "will my car be able to handle the tow and what type of set up do you recommend for towing the trailer? I look forward to your answer.

Thanks, John H…

Hi John
            The Pacifica is a great handling tow vehicle, the 116” wheelbase is longer than most SUV’s and the rear overhang is not very long. As well it has a low centre of gravity and an excellent four wheel independent suspension. So I have no safety or stability concerns with the Trail-Cruiser. You will want an equalizing hitch with 750 pound torsion bars. You should choose one that allows the ball to be as close to the bumper as possible. I would also use a friction sway control. The off the shelf hitch receivers for the Pacifica will not likely withstand the torque that these torsion bars excerpt so you may want to have the receiver lengthened and strengthened.
            My bigger concern is from a power perspective. The 3.5 is a great engine but the big 19”tires cause it to run well below its power band in third gear at highway speed.
            I would suggest changing them to 255/40R x 19”. It is available in a Pirelli P6. We have the P6’s on our Dodge Charger and I quite like the tire. This tire will give you 8% more engine RPM. It is the same diameter as the 225/60R x 16" we used on the intrepid for many years. There are two downsides to these they are not going to be great in snow and they are pretty expensive, but still cheaper than trading vehicles.
             In the past I would have been concerned about the 40 aspect ratio being too low to be durable but I have even lower 255/35 20's on my own car and they have been fine towing.  You could try towing with the Trail Cruiser with the stock tires and if you are not happy with the performance then change to the 40's. I would likely make the size change anyway when the original tires wear out. The Dealer or a good service garage can recalibrate the speedometer for you.

Andy

Hello Andy:
            As you know I own a 2005 Chrysler Pacifica AWD with the 3.5 HO engine and 4-speed automatic. The car is set up with an equalizer hitch and Reese sway control bar. We are towing an R-Vision 25' Trail Cruiser with the rear slide out. The dry weight for the trailer is said to be approximately 3800 lbs. The tires that I was running on my car were 255/50/19 tires. The advice you gave me back in July to change my tire size to 255/40/19 resulted in a very noticeable power to the pavement change. The change on the speedometer was 6%.
            We traveled into the mountainous area of Sparwood, BC from Coaldale, AB. On this day the winds were horrendously strong from the west (headwinds) at 50 kph gusting to 70-80 kph. The towing through the foothills in this wind was hard on the car (we were able to maintain 90 kph) but still achievable. Last year we towed a 17' Trail Cruiser single axle into the same area and into the same wind gusts. The larger trailer, which weighs 1000 lbs more, seemed to tow easier. Was this because of the tandem axle or the tire size? I would contribute the change in tire size as the main factor and the tandem axle setup as a small factor.
            When we came home from Sparwood to Coaldale (Lethbridge area) the winds were light from the south and the trailer towed much easier than before, especially up the hills. There seemed to be extra power which I'm sure the change in tire size contributed to this. I tow the trailer in 3rd gear at 95 kph and most of the hills were achievable in this gear. The longer and steeper hills I had to shift down to 2nd gear to maintain 80 kph. With the larger tires I was shifting into 2nd gear to maintain 80 and sometimes dropping to 70 kph on similar hills.
            I had a few people in the campground astonished that I would be towing a trailer of this length with my car. I said that the trailer was a light weight trailer and if you had the car/trailer set up properly there would be no problem. There is no need to travel at 110 kph (even though I could) to get to your destination. We got home in 2 hrs 20 min which was only 10 minutes longer than without towing the trailer. Our cruising speed was 95 kph (calculated for the difference in tire size) and we averaged 13.8 mpg with the air conditioner on and traveling through the hills at higher altitude. (Crowsnest Pass is 4500 ft ASL and Lethbridge is 3000 ft ASL)
            I would like to say thanks Andy for the great advice and we will be doing more towing feeling much more comfortable with the hills we have to negotiate.

John Harbidge, Coaldale, AB

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